A nucleotide base (guanine, adenine, cytosine,
and thymine) is one of the building blocks of
DNA, along with phosphates and sugar. These substances will join together to determine
the order of proteins in each organism.
A codon is a triplet series of bases linked
together during protein synthesis to form an
amino acid. Each codon carries the code for
a specific amino acid.
Crick's central dogma
of molecular biology, put simply, is: DNA makes RNA makes protein. This general rule emphasized
the order of events from transcription through
translation and provided the basis for much
of the genetic code research in the post double-helix
1950s. The central dogma is often expressed
as the following: DNA makes RNA,
RNA makes proteins, proteins make us.
DNA, deoxyribonucleic acid, and RNA, ribonucleic
acid, are molecules that hold the genetic information
of each cell. The DNA strands store information,
while the RNA molecules take the information
from the DNA, transfer it to different places
in the cell, and decode or read the information.
DNA takes the form of a double helix, with
repeated sugar-phosphate backbones on the outside
and paired bases making up the steps
in the middle. DNA makes up genes, each of which
contains enough information to make a specific
protein. The mixture and order of these genes
make up each organism.
Though DNA, then called nuclein, was first
isolated back in 1869, it was not until the
second half of the twentieth century that scientists
began to fully understand the importance of
DNA and its relationship to hereditary characteristics.
Escherichia coli, or E. coli as it is usually
known, is a one-celled organism. The cell has
no nucleus, and its DNA is in the form of one
long looping molecule. E. coli is a commonly
available bacterium, plentiful in the human
colon, and therefore often used for experimental
A genome is the name for the entire set of unique
DNA that makes up a particular organism.
A protein is a molecule that performs chemical
reactions necessary to sustain the life of an
organism. One cell can contain thousands of
The ribosome is the place in the cell where
groups of bases called codons are translated
into amino acids.